AUGUSTA — Legislative Democrats said Wednesday they will try to persuade their Republican colleagues to stick by their earlier votes and pass a $20 million borrowing proposal for research and development projects as lawmakers consider whether to override vetoes of that measure and three other bills by Gov. Paul LePage.

The House and Senate will return to the State House on Thursday for the possible override votes as they formally close the 2011-12 legislative session.

Minority Democrats set the tone for debate Wednesday when they said the governor is turning his back on new jobs, spinoff economic activity and matching funds that would be generated by the research and development borrowing.

The measure was the only one of five bond issues totaling nearly $100 million that the governor vetoed. In LePage’s message asking lawmakers to uphold his veto, he said that if lawmakers really want to spend on R&D, “then we should reduce spending elsewhere in the budget and pay for it out of the General Fund.”

Funds raised by the bonds would have to be allocated to any of an array of technologies, including environmental, renewable energy, aquaculture, composite materials, marine and biotechnology. Grants would be awarded through a competitive process to Maine-based public and private institutions.

“The governor is turning away good-paying jobs, future innovation and economic opportunities for our state,” said Assistant Senate Democratic Leader Justin Alfond of Portland. “We urge our Republican colleagues to make the right choice for Maine’s economy.”

Democrats say every dollar of R&D funds returns $12 in economic benefits to the state. But LePage has questioned distribution of funds to nonprofits and government agencies.

“Taxpayer dollars should go towards R&D only when we can demonstrate a specific return on investment,” LePage wrote in his message to lawmakers. “That return must be measured in taxes and jobs. Both of those rightly come in the private sector.”

The bond issue has already passed by more than two-thirds majorities in the House and Senate, the same supermajority it would take to override LePage’s veto. So the bill’s fate depends on how many lawmakers — especially Republicans — are influenced by the governor’s veto to change their votes.

LePage also vetoed a bill to limit the borrowing power of the Maine Governmental Facilities Authority, an agency that has long been the target of GOP criticism because of its ability to borrow without voters’ approval. The bill initially would have eliminated that power, but it was amended so court bonds would not have to go to voters.

“While I strongly support the judicial branch, why should they receive special treatment?” the governor wrote. “Our Constitution gives us three co-equal branches of government. We must have consistency among them.”

Another vetoed bill would have increased stipends for teachers who achieve an advanced credential known as National Board Certification and provided scholarships for teachers undertaking the costly and time-consuming process. The governor said it didn’t go far enough and said the state needs “a larger more coordinated statewide solution.”

The final bill seeks to allow fraternal and veterans’ organizations to operate up to five slot machines each. While acknowledging that veterans’ organizations that supported the bill would be upset by his veto, LePage said the issue should be decided by Maine voters.